Question: What is the greatest common factor of $5$ and $10$ ? Another way to say this is: $\operatorname{gcf}(5, 10) = {?}$
Solution: The greatest common factor is the largest number that is a factor of both $5$ and $10$ The factors of $5$ are $1$ and $5$ The factors of $10$ are $1$ $2$ $5$ , and $10$ Thus, the greatest common factor of $5$ and $10$ is $5$. $\operatorname{gcf}(5, 10) = 5$